Fluid:[✎ edit | edit source]
A fluid is a gas or liquid that, unlike a solid, flows to assume the shape of the container in which it is placed. This occurs because a fluid responds to a shear stress, or a force per unit area directed along the face of a cube of fluid, by flowing, rather than by an elastic displacement as in a solid.
PROPERTIES OF FLUID[✎ edit | edit source]
Density of a fluid is defined as the ratio of the mass of a fluid to its volume.
Specific volume of a fluid is defined as the volume of a fluid occupied by a unit mass or volume per unit mass of a fluid.
3.VISCOSITY OF LIQUID:
Viscosity is defined as the property of a fluid which offers resistance to the movement of one layer of fluid over another adjacent layer of fluid.
TYPES OF FLUIDS BASED ON VISCOSITY:[✎ edit | edit source]
The fluids may be classified into following five types:
- Ideal fluid
- Real fluid
- Newtonian fluid
- Non-Newtonian fluid
- Ideal plastic fluid
Ideal fluid[✎ edit | edit source]
An ideal fluid is a fluid that has several properties including the fact that it is:
• Incompressible – the density is constant • Irrotational – the flow is smooth, no turbulence • Nonviscous –(Inviscid) fluid has no internal friction ( η = 0)
Ideal fluid do not actually exist in nature, but sometimes used for fluid flow problems.
2.Real fluid: Fluid that have viscosity(μ > 0) and their motion known as viscous flow.
All the fluids in actual practice are real fluids.
we use ideal fluid in 2 equations :
3. Newtonian Fluids:
A real fluid in which the shear stress is directly proportional to rate of shear strain (or velocity gradient).
4. Non-Newtonian Fluid:
A real fluid in which the shear stress is not proportional to the rate of shear strain.
5. Ideal Plastic Fluid:
A fluid in which shear stress is more than the yield value and shear stress is proportional to the rate of shear strain (or velocity gradient).